The School of Arts & Sciences

Department of Natural Sciences

Roy Khalaf

Dr. Roy Khalaf joined LAU as an assistant professor of biology, after completing a one-year post-doctoral fellowship at the Georgetown University Medical Center. He is currently an associate professor and Chairperson of the Department of Natural Sciences. His research interests revolve around the opportunistic filamentous fungal pathogen, Candida albicans, one of the leading causative agents of death in immunocompromised individuals.

His team is currently working on identifying key genes that confer virulence to this organism. Many of these factors they are currently studying are cell wall proteins involved in adhesion and degradation of the host tissue for successful infection. His lab is currently generating homozygous null mutants by marker cassette recombination and integration and comparing the mutant to the wild type phenotype as far as filamentation ability, antifungal drug resistance, virulence in a mouse model, adhesion to epithelial and endothelial cells, and macrophage interaction. Furthermore his team is analyzing the cell surface proteome of these mutants through liquid chromatography and MALDI TOF mass spectrometry in an effort to determine key cell surface proteins. Moreover, they are also in the process of typing various C. albicans isolates from Lebanese hospital patients by MLST, PFGE , whole genome sequencing, and testing the susceptibility of these isolates to novel antifungal drugs in an effort to improve treatment of candidiasis and the well-being of patients.

Publications

  1. Deckert J, Khalaf RA, Hwang SM, and Zitomer RS. Characterization of the DNA binding and bending HMG domain of the yeast hypoxic repressor Rox1. Nucleic Acids Research 1999 ; 27(17): 3518-26.
  2. Khalaf RA, and Zitomer RS. The DNA binding protein Rfg1 is a repressor of filamentation in Candida albicans. Genetics 2001;157 (4):1503-12.
  3. Limijindaporn T, Khalaf RA, and Fonzi WA. Nitrogen metabolism and virulence of Candida albicans requires the GATA-type transcriptional activator encoded by GAT1. Molecular Microbiology 2003;50 (3), 993-1004.
  4. Yazbek S, Barada G, Basma R, and Khalaf RA. Significant discrepancy between Real Time PCR identification and hospital identification of C. albicans isolates from Lebanese hospital patients. Medical Science Monitor 2007. 13(5); MT7-12.
  5. Barada G, R. Basma R, and Khalaf RA. Candida albicans Identification and Genotyping in Lebanese Clinical Isolates Through Microsatellite DNA Polymorphism. Mycopathologia 2008;165(3):115-25.
  6. Dib L, Hayek P, Sadik H, Beyrouthy B, and Khalaf RA. The Candida albicans Ddr48 Stress Response Protein is Essential for Filamentation, Virulence, and Confers Partial Antifungal Drug Resistance. Medical Science Monitor 2008;14 (6):BR113-121.
  7. Basma R, Barada G, Ojaimi N, Khalaf RA. Susceptibility of Candida albicans to common and novel antifungal drugs, and relationship between the mating type locus and resistance, in Lebanese hospital isolates. Mycoses. 2009, 52(2):141-8.
  8. Bitar M, Khalaf R, Sabbagh A, Shamseddine W, El Hajj N, Zaatari G, Fuleihan N, Greige L, Mahfouz R Killer Cell Immunoglobulin-like Receptor (KIR) Genotypes in patients with recurrent tonsillitis. Genetic Testing and Molecular Biomarkers. 2008, 12(4):517-521
  9. Mahfouz R, Sabbagh S.A, Khazen G, El Hajj N, Rayes R, Arayssi TK, Zaatari G.S, Khalaf R.A. Distribution of Killer Cell Immunoglobulin-like Receptor (KIR) Genotypes in Patients with Familial Mediterranean Fever. Genetic Testing and Molecular Biomarkers. 2009, 13(1): 91-95
  10. Hayek P, Dib L, Yazbeck P, Beyrouthy B, Khalaf RA. Characterization of Hwp2, a Candida albicans GPI anchored cell wall protein necessary for invasive growth. Microbiological Research 2010 Mar 31;165(3):250-8
  11. Ramsook C, Tan C, Garcia MC, Fung R, Soybelman G, Henry R, Litewka A, O’Meally S, Otoo H.N, Khalaf R.A, Dranginis A, Gaur N.K, Klotz S.A, Rauceo JM, Jue C.K, Lipke P.N. Yeast Cell Adhesion Molecules Have Functional Amyloid Forming Sequences. Eukaryotic Cell 2010 Mar;9(3):393-404.
  12. Hashash R, Younes S, Bahnan W, El Koussa J, Maalouf K, Khalaf RA. Characterization of Pga1, a Candida albicans Cell Wall Protein necessary for proper adhesion and biofilm formation. Mycoses. 2011 Nov;54(6):491-500
  13. Younes S, Bahnan W, Khalaf RA. The Candida albicans Hwp2 is necessary for proper adhesion, biofilm formation and oxidative stress tolerance Microbiological Research. 2011 Jul 20;166(5):430-6
  14. Daher J, Younes S, Koussa J, Khalaf RA. Characterization of Dse1, a Candida albicans essential cell wall protein. Interdisciplinary Perspectives on Infectious Diseases. 2011;2011:504280.
  15. Bahnan W, Koussa J, Younes S, Abi Rizk , Khalil B, El Sitt S, Hanna S, El Sibai M, Khalaf R.A. Deletion of the Candida albicans PIR32 results in increased virulence, stress response, and upregulation of cell wall chitin deposition. Mycopathologia. 2012 Aug;174(2):107-19
  16. Younes S.S, Khalaf RA. The Candida albicans Hwp2p can complement the lack of filamentation of a Saccharomyces cerevisiae muc1 null strain. Microbiology. 2013 Jun;159(Pt 6):1160-4.
  17. Khalaf R, Hoteit R, Yazbek S, El Hajj N, Otrock Z, Khansa S, Sabbagh A, Shammaa D, Mahfouz RA. Natural Killer Cell Immunoglobulin-like Receptors (KIR) Genotypes in Follicular Lymphoma patients: Results of a pilot study.Gene. 2013 Aug 1;525(1):136-40.
  18. Bitar I1, Khalaf RA1, Harastani H, Tokajian S. Identification, Typing, Antifungal Resistance Profile, and Biofilm Formation of Candida albicans Isolates from Lebanese Hospital Patients. 1 Both authors contributed equally to the work. Biomed Res Int. 2014;2014:931372.
  19. Zohbi R, Wex B, Khalaf RA. Comparative proteomic analysis of a Candida albicans DSE1 mutant under filamentous and non-filamentous conditions. Yeast. 2014 Nov;31(11):441-8. 

Academic degrees

 


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